Those Ducati Winglets: What Are They Really For?

The Ducati Desmosedici MotoGP bike has always been famous for its top speed, a characteristic which is generally put down to two things: the first is the 16-valve V4 desmodromic engine, the brainchild of Ducati Corse director Filippo Preziosi, which has long been the most powerful engine on the grid. The second factor is the Bologna company's focus on aerodynamics, an area that other factories have spent much less time and attention on. The extremely slippery nature of the Ducati Desmosedici is in large part due to Ducati Corse's use of former F1 engineer Alan Jenkins as an aerodynamics consultant.

Jenkins has worked ceaselessly with Ducati over the years to improve the aerodynamics of the Desmosedici, and the German Grand Prix at the Sachsenring saw a new innovation appear on the fairing of the bike. The Ducati had sprouted a pair of "winglets" (shown below) - protruberances sticking both forward and out of the side of the fairing, at about the height of bottom of the fork outer. Naturally, these strange additions aroused the curisoity of the assembled media, who set about trying to fathom their purpose.

Questions aimed at Ducati riders Casey Stoner and Nicky Hayden did not produce any usable information, both men merely replying that they could not really feel much difference. The general consensus - prodded by some inside information - was that the point of the winglets was to increase downforce at high speed, and prevent the bike's propensity to lift the front wheel. That story was mulled over by the assembled wise heads in the paddock, and generally assumed to be probably accurate.

But just how correct that supposition is remains to be seen. For after an astute post by one member of MotoMatters.com, there are reasons to believe that the downforce idea is little more than smoke and mirrors. For a start, the surface area involved is relatively small, most likely too small to have much of an effect at the required velocities. Figures being bandied about the paddock suggested that the winglets contributed around 10 kg of downforce at 300 km/h, which would be enough to prevent the front wheel from lifting.

That figure may be correct, but preventing the front from lifting is far more of a problem at 200 km/h than it is at 300 km/h. At that point, the bike is under hard acceleration, and is wanting to lift the front. Anti-wheelie software can help here, but that relies on cutting power, something that reduces drive out of the corners. Some form of aerodynamic assistance would be of more use than cutting power, but due to the exponential nature of fluid dynamics (air resistance - and the effectiveness of flaps and winglets - is squared when speed doubles), the effectiveness of the winglets is likely to be around half that 10 kg figure at 200 km/h. And the slower you go (and therefore, the harder you are accelerating), the less effective the winglets become.

But while the focus has been almost entirely on the horizontal surfaces, the real magic is probably being created by the vertical flaps. The inverted shark fin shapes sticking out below the protrusions appear to be shaping airflow along the side of the fairing, and reducing the air pressure behind the winglets. The horizontal protrusions could be part of a scheme to increase the airflow past the vertical fins, which as a result of the Venturi effect reduces the pressure behind the fins.

And what do we find directly behind those winglets? The radiator vents, where hot air from the radiator is being forced out of the fairing, dispersing the heat from the Desmosedici engine, a notorious problem for the Ducati. The problem with the bare radiator vents is that the air exiting the vents hits the wall of air at the side of the fairing, reducing the flow from the vents. The vents are shaped to smooth and maximize the airflow around the vents, but the usual fairing design soon runs into limits with how much the venting of hot radiator air can be optimized.

The winglets - and especially the vertical flaps - produce an extra pressure drop over the radiator vents by accelerating the flow over them. That decrease in pressure sucks more hot air out of the radiator vents, which in turn draws more cool air through the radiator, allowing the engine to run cooler. The location of the winglets is directly ahead of the largest part of the radiator vents, and the place which would produce the most benefit from increased airflow. The shape of the vertical flaps also suggests they could play a role in smoothing airflow over the vents, and separating the boundary layer from the vent.

The idea that the winglets seen on the Ducati are more to do with cooling than with downforce has a lot of things going for it. First and foremost, it fits in with the biggest change in MotoGP this season, the restrictions on the numbers of engines which may be used. With just 6 engines per season for each rider, engine longevity becomes crucial, and one of the key elements in securing that longevity is engine temperature. The lower the temperature the engine operates at, the longer it will last. Ducati MotoGP bikes have always run extremely hot - the factory was forced to drill holes in the fairing on the first version of the bike back in 2003, to prevent the heat from the engine from causing heat blisters on the hands of Loris Capirossi and Troy Bayliss - and though the issue has been worked on throughout the bike's history, the Ducati still generates an awful lot of heat.

So an aerodynamic solution to reducing the operating temperature is not only plausible, but extremely likely, given Ducati's interest in the area. The size, shape and location of the winglets suggest that this is exactly what Ducati have been trying to achieve, to cool the engine by producing better airflow through the radiators, with the winglets in effect sucking the hot air out of the back of the vents more efficiently.

Whether this was the intent of Alan Jenkins and Filippo Preziosi when they put this solution together or not will probably remain a secret, at least for the time being. The talk of increasing downforce helps create confusion and may be helping to cover Ducati's tracks. The fact that the MotoGP paddock - as full of brilliant minds as it is - has neither the experience nor the interest (one Moto2 bike designer dismissed the idea of aerodynamics as a factor in motorcycle racing as completely irrelevant) in understanding the implications of aerodynamics innovations merely plays into Ducati's hands even further.

I can claim no credit for the ideas in the above article: They were taken from the comments by MotoMatters.com member Oscar both on the main site as well as on the forum, and mixed up with othercomments from forum members until the above synopsis emerged. Any credit belongs to them, and any errors are entirely mine.

It's amazing the continuous development that you see in Formula One - flexing wings, possibly flexing car floors, exhaust-driven diffusers, "f-ducts" and on and on. It's an expensive route, but I imagine this is just the start for motorcycles.

Form follows functions. Let us hope in the case of MotoGP and other racing motorcycles that they will look natural and aesthetic. Aim for the McLaren MP4/5, MP4/6, and MP4/7, not for the McLaren MP4-25.

At the Busy Little Shop I design and machine parts for experimental
aircraft... When you wild ass guess any new aerodynamic appendage you
must begin thinking what the air is doing at the very front of the
machine as it cuts the flow... I think Ducati noticed something in the
wind tunnel test in keeping the flow attached and minimizing the wake
turbulences which is very important at 200mph +... I think they
noticed how the air flow tumbled off the front fender / fork and then
wanted to smoothly attach that disturbed air against the fairing to
not only lower the coefficient of drag but also to generate a little
jet of air to assist the air flow exiting the radiator duct... every
little bit helps... Lets not forget that in 2003 Ducati was off the
top of the top speed charts until the last round at Valencia... this
was due to the extra drag created by the additional ducting along with
larger 50mm diameter forks...
Larry L
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I read somewhere that it was in response to a letter from a small child. The story goes, 10 year old Adil from Kuala Lampur wrote to Philip Morris to ask where Nicky and Casey set their cigarettes while riding. As smoking is forbidden in the paddock, the boy new the riders must be enjoying the smooth, mild flavor of Marlboro products while out on the track. As to not disillusion the customer, err, I mean, child with images of the riders just tossing the butts on the side of the riding line, PM encouraged Preziossi to commission the stylish receptacles be added to the fairings. Thus the wing was born. Sensible design follows sensible tobacco consumption.

You have just nailed the point. The forks are an issue and the new forks limit cooling because of their size. The winglets might just counter that by increasing airflow, allowing them to get back to working on configuration rather than worrying about over-heating.

Of course, it seems that Stoner has gone back to the smaller tube forks.

I can recall a video segment (Julian Ryder's "expert eye"?) about the cooling on the Kawasaki machine and the crew member describing that on some tracks they would remove the front fender to allow for greater cooling. It was a giant radiator, if I recall correctly. Very impressive.

All joking aside. The wings are pretty cool and stuff but it was always my impression that the technology developed in MotoGP was for the deliberate purpose of furthering road going motorbikes via the trickle down effect, (e.g. Yamaha's Cross-Plane Crank and so forth). At least that was the premise I thought was supposed to be occuring...

"one Moto2 bike designer dismissed the idea of aerodynamics as a factor in motorcycle racing as completely irrelevant"

I remember (many, many) years ago Performance Bikes doing a nice article on a 125 racer. With the journo on board, the bike had a top speed of 129.5mph, but with the racer it managed 134.5mph. This was apparently all down to the racers better tucking in skills.

(I don't remember the speeds exactly, but there was about a 5mph diff.)

There is really no such thing as "down force" when discussing a leaned-over motorcycle. Adding load aerodynamically to either tire while the bike is leaned over is a recipe for disaster... even if it were possible. If anything, they would rather try to generate lift, but the device would be so subject to crosswinds that it would be dangerous in anything more severe than a slight breeze.

The trick is to create something that is as neutral as possible while leaned over, but still generating the desired effect going straight. That is a drastically different principle than designing for cars.

The winglets are to assist the rider in lifting his crashed bike by keep the bike from lying too flat. If you check closely, you'll find that Casey's winglets are slightly larger than Nicky's as Casey isn't as strong as Nicky so he'd need the larger winglets to right his bike. If Dani ever races for Ducati, his winglets will be the size of a milk crate.

Small point - but better cooling also means you can run a leaner mixture for longer without detonation ( i.e. not wasting fuel for cooling purposes) thus giving a smidgeon more usable fuel for power delivery over race distance. Every bit helps. Given Honda's apparent somewhat thirsty nature, I'd not be surprised to see them be amongst the first of the rest to look for a similar sort of advantage, though that need not be 'winglets' per se - vortex generators (little blades sticking out from the surface of the fairing at 90 degrees) could be the next easy fix, they can be stuck on with epoxy glue..

However there's always a price to be paid. Make the fairing more efficient at holding the airflow past the cooling exhaust openings and you could also increase its efficiency as a (vertical) lifting surface in side-winds, making the bike more unstable at speed in a crosswind.

If JB and VR join Ducati next year, I can see a potential for real conflict as neither of them will be particularly interested in re-inventing the wheel and JB in particular is particularly dismissive of overly complicated solutions to simple problems. I suspect Alana Jenkins will get squeezed out very quickly.

I cant wait to see what happens in the chassis department next year as that seems to me to be the area that JB and VR will attack hardest first. Both are used to sweet handling agile bikes and the Duc's long and low nature wont appeal to either of them.

thanx David, and Oscar: the Quest for Truth on the Ducati Widgets really sums up well intelligent motorbike journalism and interaction with a forum filled with inquisitive and knowledge-hungry readers/participants.

These are very similar to the turning vanes seen on most F1 cars now and serve the same purpose of controlling airflow. These would definitely aid the extraction of air from the radiator exits.
Rusty Bucket makes a good point though, when the bike is at max. lead angle the wing shape at the top of the device would be generating downforce at the same angle as the suspension. I think that it's likely that this force added to the centrifugal force acting on the center of gravity would have an adverse effect on traction and this may be the reason Casey Stoner tucks the front so much. Thoughts?

Someone else pointed me to those winglets. The difference between those winglets and the ones on the Ducati is that the Suzuki ones were higher and further forward. Far more importantly, however, they did not have the vertical component, the shark fin underneath. That is the key element, the part that tells you that there's more to this than downforce

My small displacement experience with my large displacement physique makes lifting the front end under hard acceleration a non-issue. But how does it actually slow the rider down? Is it that they have to let off the gas to not flip over? Is it that there is energy wasted lofting (and holding) the bike in the air that could be used to go forward? Or is a lack of aerodynamics that a raised front end presents? I'd think the lower rolling resistance due to the front wheel drag being absent would be a plus!

not really! it's just worse with both off the ground. you can do the maths if you want to but for a given angle of incline the machine is rotating around the sprocket and therefore not going forward as fast as a machine planted on the ground. In certain circumstances you would also need to back off the throttle opening to prevent an MB back flip scenario, it's all fractions of course but races have been won and lost by those fractions.

It seemed intuitive that it was the idea of the increased angle around the axle being subtracted from the angular velocity going forward. But then I thought that the angle of elevation should only equate to a few inches of linear loss. While races can be won by that much, it seems as though when they wheelie too much out of a corner that they loose a bike length or more. So that's why I wondered if it was the backing off of the throttle or my calculations of the linear losses that were wrongly imagined.

When a bike starts to wheelie and the front wheel comes off the ground the center of gravity of the machine rises. When the C of G height increases it makes the bike easier to wheelie. With the same acceleration rate if a bike starts to wheelie it then wants to wheelie even more, thus positively reinforcing the wheelie tendency. Like all positive feedback mechanisms this will quickly lead to gross instability (flipping over) unless the rider (or ecu) introduces a negative feedback signal (rolling off the throttle) to counter the wheelie's effects. So the only way to get the front wheel back on the ground is to back off the throttle to reduce the acceleration _below_ the original level that initiated the wheelie. It is this rolling off to a lower acceleration rate to re-plant the front tire which is where the bike lengths of loss come from.

An early generation model of John Britten iconic motorcycle had a couple of winglet protuberances at around clip-on height. I recall Sir Anal Bathfart mentioning after a test ride at Ruapuna that these adversely affected the handling of the motorcycle. The wings were clipped shortly thereafter. Kiwi's were never mean't to fly.

Surely the Ducati winglets were merely put in place to try and entice a healthy dose of Red Bull sponsorship?

One thing that people seem to not think about, but if air gets under those wings for any reason, they'll provide LIFT. As in, if for some reason the acceleration exceeds the downforce provided by the winglets, they'll end up creating a flap effect (actually the entire underside of the bike already does that somewhat when you're doing a wheelie anyway).

That may be true to an extent but in resent comments Casey has spoken about not 'trusting', or not 'feeling' feedback for the front.
The amount of downforce from this wing feature would of course vary with the bike's cornering speed and be affected by sidewinds and the turbulence from other bikes, just like in F1 where the drivers all complain about these problems.
I would suggest that Ducati retain the turning vane, the vertical part of the appendage and eliminate the top wing form. This may improve the riders feel from the front and actually increase traction while still providing the extractor effect for the radiator.
I remain convinced that the small amount of downforce which is not pushing the tire down but in the direction of the suspension angle is contributing to overcoming the traction of the tire causing it to lose it's grip on the track's surface.

As an old hang glider pilot it looks to me like (based on the pics above) the only real value the fins can have is to create a more laminar flow across the radiator "exhaust" area.

At higher speeds there will be significant down flow from the upper part of the fairing that will conflict with the horizontal flow. These fins would assist in directing that downward flow more in line with the flow from the front of the bike. This would create a greater vacuum in the exhaust area and the pressure at the front (intake) to the radiator will be relatively more influential. the end result is more air flow thru the radiator and cooler water temperature.